POS1421 AROMATASE INHIBITORS AND SKELETAL HEALTH – NATURAL HISTORY AND INTERVENTIONAL EPIDEMIOLOGY
Authors: A. Mirza, Z. Win Naing, P. Khonsari, H. Khan, P. Rezai, A. K. Abbas, M. Nisar
Journal: Annals of the Rheumatic Diseases (2022)

Background Breast cancer remains the most common cancer diagnosed in women worldwide. Aromatase inhibitors (AI) are employed for hormone sensitive disease in mainly postmenopausal women. AI related bone loss (AIBL) is a known complication; although data regarding the natural history in the real-world, long-term outcomes and the role of bone active therapy in fracture prevention is sparse. Objectives Our aim was to determine the real-world impact of AIBL and whether bone sparing therapy utilising standard risk stratification model is sufficient for fracture prevention. Methods We undertook a longitudinal study of patients prescribed AI for breast cancer over a seven-year period at our university teaching hospital. All the data was recorded electronically with full access to demographics, disease parameters, investigations and drug management. DEXA scans performed prior to initiation of AI were compared with subsequent imaging over a mean follow up of 3 years. Outcome data for cancer and all fractures was collected. Statistical analysis was done to investigate significant relationships amongst the variables of interest. Results 1001 women were identified during the study period. The mean age of the cohort was 64 years (range 29-93). 929 (93%) were Caucasian, 57 (6%) were Asian and 15 (1%) were Afro-Caribbean. 723 women (72%) were diagnosed with invasive ductal carcinoma and 863 women (86%) were postmenopausal. At diagnosis, 428 women (43%) had node positive disease and 35 women (4%) had metastases. 91 women (9%) had sustained fractures prior to their breast cancer diagnosis. All women had a baseline DEXA: 496 (49.6%) had osteopenia, 151 (15%) had osteoporosis and 354 (35.4%) had a normal result. 478 (48%) of women had a repeat scan available. Overall, there was a decline (from a mean of 0.888 g/cm2 to 0.858 g/cm2, p&lt;0.0001) in left neck of femur (LNOF) bone mineral density (BMD) over time (mean of 3 years, with a range of 1-6). 334 (33%) were prescribed bone active therapy with 276 women (83%) given oral bisphosphonates. This group had an improvement in BMD by 0.4% (LNOF mean BMD of 0.785 g/cm2 at baseline compared to LNOF mean BMD of 0.788 at repeat DEXA, p=0.82). Women who were not offered any treatment (n=667, 66%), showed a significant decline in bone density with the decline being -5%. (LNOF mean BMD of 0.939 g/cm2 at baseline compared to LNOF mean BMD of 0.888 g/cm2 at repeat DEXA, p&lt; 0.0001). The rate of fractures remained the same between the treatment (19 fractures, 5.67%) and non-treatment group (38 fractures, 5.70%) Conclusion Our study provides long term data for AIBL and confirms a significant decline in BMD over seven years. It confirms that bone sparing therapy is effective in reducing the pace of decline in BMD. However standard risk stratification model such as FRAX based intervention thresholds in mainly those with WHO defined osteoporosis (T ≤-2.5) is ineffective in fracture prevention in keeping with prior literature. Since our study period overlaps with publication of newer guidelines recommending different T score-based risk model, further studies are required to confirm their utility. References [1] https://www.wcrf.org/dietandcancer/worldwide-cancer-data/ . Date accessed: 26.01.2022 [2]R. Coleman, J.J. Body, M. Aapro, et al., Bone health in cancer patients: ESMO clinical practice guidelines, Ann. Oncol. 25 (Suppl 3) (2014) iii124–iii137. [3]E. Amir, B. Seruga, S. Niraula, et al., Toxicity of adjuvant endocrine therapy in postmenopausal breast cancer patients: a systematic review and meta-analysis, J. Natl. Cancer Inst. 103 (2011) 1299–1309. Disclosure of Interests None declared